Firearm upper receiver

ABSTRACT

A magnesium alloy firearm upper receiver having a functional life of at least 500 firearm actuation cycles. The firearm upper receiver having a magnesium alloy housing defining an upper receiver cavity having an interior surface shaped and sized to enable actuation of a bolt carrier group therein during a firearm actuation cycle, at least a portion of the interior surface coated with a hardened anodized coating configured to slow operational wear of the interior surface generated by heat, pressure and frictional forces during a firearm actuation cycle.

RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 62/910,985 filed Oct. 4, 2019, U.S. ProvisionalApplication No. 62/963,844 filed Jan. 21, 2020, and U.S. ProvisionalApplication No. 63/058,318 filed Jul. 29, 2020, each of which is herebyincorporated herein in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates generally to firearm upper receivers, andmore particularly to a magnesium alloy upper receiver for use infirearms including the AR-10, AR-15, M-16, and variants thereof.

BACKGROUND

The ArmaLite AR-10 was developed by Eugene Stoner in the late 1950s as alightweight assault rifle for military use. The basic AR-10 design had adirect impingement, rotating bolt configured to accept 7.62×51 mm NATO(.308 Winchester) cartridges. In 1957, the AR-10 design was rescaled andsubstantially modified by ArmaLite to accommodate 5.56×45 mm NATO (.223Remington) cartridges, and given the designation AR-15. ArmaLite soldits patent rights to the AR-10 and AR-15 to Colt Firearms in 1959. Aftersubsequent modifications, the AR-15 was adopted by the US military asthe M-16 rifle. With the expiration of the ArmaLite patents in 1977,other manufacturers began producing their own variants of the firearm,commonly known as AR-15 style rifles.

Today, the AR-15 rifle has become one of the most beloved rifles in theUnited States, and has been referred to as “America's rifle” by theNational Rifle Association (NRA). One innovative feature of the AR-15rifle is its distinctive two-part upper and lower receiver and itsmodular design enabling ease in the interchangeability and replacementof parts. As civilian ownership of AR-15 style rifles grew, numerousmanufacturers began producing “improved” aftermarket modules,assemblies, or parts with features not found on factory rifles. Due tothe modular construction of AR-15 rifles, individuals with an averagemechanical aptitude can substitute aftermarket parts with the originalfactory parts to customize their rifle. Due to the vast assortment ofaftermarket parts and accessories currently on the market, the AR-15style rifle has been referred to as the “Swiss Army knife of rifles.”

FIG. 1 depicts a partial cross-sectional view of an AR-15 rifle 100generally including an upper receiver group 102, lower receiver group104, stock 106, and barrel 108. The upper receiver group 102 cangenerally be seen as the upper half of the rifle 100. The upper receivergroup 102 can include a bolt carrier group 110, charging handle 112,ejection port dust cover (not depicted), forward assist (not depicted),and the upper receiver housing 114 which encapsulates and combines thesecomponents. The upper receiver housing 114 can have a flat top with apicatinny rail 116 or it can have a carry handle (not depicted).

The lower receiver group 104 contains all of the parts needed to firethe rifle 100, such as a trigger group 118, magazine well 120, and grip122. According to the laws of many countries, the lower receiver 102 isthe part of the rifle 100 that is considered to be the firearm itself(rather than just a component), and therefore typically carries theserial number of the firearm 100. The lower receiver group 104 istypically joined to the upper receiver group 102 with two takedown pins124A-B. The stock 106 is attached to the rear end of the lower receivergroup 104. The barrel 108 is attached to the front end of the housing114 of the upper receiver group 102.

The upper receiver housing 114 (referred to hereinafter as the “upperreceiver” or “upper”) is generally considered an interchangeablecomponent of the firearm 100, as it does not carry the serial number ofthe firearm 100. Presently, a variety of upper receivers 114 arecommercially available. In general, the upper receivers 114 currentlyavailable on the market are designed to accommodate barrels of differentweights, lengths and calibers. As AR-15 rifles are commonly carried forlong distances and durations by police, hunters and sportsmen, a desireexists to lighten or otherwise reduce the overall weight of the upperreceiver 114.

The present disclosure addresses this concern.

SUMMARY OF THE DISCLOSURE

As discussed in various forums, past efforts have been made to constructan upper receiver out of a lightweight magnesium metal alloy; however,such efforts have been met with little success, as to date no magnesiummetal alloy has been found that can withstand the heat, pressure andfrictional forces generated from cycling the rifle 100 over anappreciable duration (e.g., functional usage for at least 500 firearmactuation cycles). As a result, to the extent that any magnesium uppershave been produced, durability has been a major concern.

Embodiments of the present disclosure provide lightweight, corrosion andabrasion resistant magnesium firearm upper receivers, configured tolighten or otherwise reduce the overall weight of AR-10 rifles, AR-15rifles, M-16 rifles and variants thereof, while ensuring a functionallife of at least 500 firearm actuation cycles, and in many cases morethan 10,000 firearm actuation cycles. Various apparatus embodiments andmethods of manufacturing magnesium upper receivers are disclosed herein.

One embodiment of the present disclosure provides a firearm upperreceiver including a magnesium alloy housing defining an upper receivercavity having an interior surface shaped and sized to enable actuationof a bolt carrier group therein during a firearm actuation cycle,wherein at least a portion of the interior surface is coated with ahardened anodized coating configured to slow operational wear on theinterior surface generated by heat, pressure and frictional forcesduring a firearm actuation cycle to ensure a functional life of themagnesium alloy housing over at least 500 actuation cycles.

In one embodiment, the hardened anodized coating includes amagnesium-oxide layer. In one embodiment, the magnesium-oxide layerincludes one or more hardening agents embedded therein. In oneembodiment, the hardened anodized coating is treated with a topcoatsurface treatment. In one embodiment, the topcoat surface treatment isat least one of an electrophoretic paint and/or lubricity enhancingagent.

In one embodiment, the firearm upper receiver further includes a brassdeflector. In one embodiment, the brass deflector is constructed of amaterial other than magnesium alloy. In one embodiment, the brassdeflector is positionable relative to the magnesium alloy housing withina deflector channel defined by the magnesium alloy housing. In oneembodiment, the brass deflector includes a deflecting surface configuredto impart directional control on brass ejected from the magnesium alloyhousing during firearm actuation.

Another embodiment of the present disclosure provides a method of makinga firearm upper receiver, including: machining a housing including anupper receiver cavity out of a stock of extruded magnesium alloy; andapplying a hardened anodized coating to at least a portion of aninterior surface of the upper receiver cavity to slow operational wearon the interior surface generated by heat, pressure and frictionalforces during a firearm actuation cycle to ensure a functional life ofthe housing over at least 500 firearm actuation cycles.

Another embodiment of the present disclosure provides a firearm upperreceiver kit including a magnesium alloy housing defining an upperreceiver cavity having an interior surface coated with a hardenedanodized coating configured to slow operational wear on the interiorsurface generated by heat, pressure and frictional forces during afirearm actuation cycle, and one or more brass deflector including adeflecting surface configured to impart directional control on brassejected from the magnesium alloy housing during firearm actuation.

The summary above is not intended to describe each illustratedembodiment or every implementation of the present disclosure. Thefigures and the detailed description that follow more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more completely understood in consideration of thefollowing detailed description of various embodiments of the disclosure,in connection with the accompanying drawings, in which:

FIG. 1 is a partial, cross-sectional, perspective view depicting anAR-15 rifle.

FIG. 2A is a perspective view of a magnesium alloy upper receiver, inaccordance with an embodiment of the disclosure.

FIG. 2B is a right side view depicting the magnesium alloy upperreceiver of FIG. 2A.

FIG. 2C is a top view depicting the magnesium alloy upper receiver ofFIG. 2A.

FIG. 2D is a left side view depicting the magnesium alloy upper receiverof FIG. 2A.

FIG. 2E is a bottom view depicting the magnesium alloy upper receiver ofFIG. 2A.

FIG. 2F is a proximal end view depicting the magnesium alloy upperreceiver of FIG. 2A.

FIG. 2G is a distal end view depicting the magnesium alloy upperreceiver of FIG. 2A.

FIG. 2G is a distal end view depicting the magnesium alloy upperreceiver of FIG. 2A.

FIG. 2H is a bottom perspective view depicting the magnesium alloy upperreceiver of FIG. 2A, including details of the upper receiver cavity inaccordance with an embodiment of the disclosure.

FIG. 3 is a schematic diagram depicting a system for applying ananodized coating to an upper receiver, in accordance with an embodimentof the disclosure.

FIG. 4 is a flowchart depicting a method of making an upper receiver, inaccordance with an embodiment of the disclosure.

FIG. 5 is a perspective view depicting ejection of brass from amagnesium alloy upper receiver, in accordance with an embodiment of thedisclosure.

FIG. 6A is a plan view depicting a brass deflector, in accordance with afirst embodiment of the disclosure.

FIG. 6B is a plan view depicting a brass deflector, in accordance with asecond embodiment of the disclosure.

FIG. 6C is a plan view depicting a brass deflector, in accordance with athird embodiment of the disclosure.

FIG. 7 is a perspective view depicting a brass deflector, in accordancewith a fourth embodiment of the disclosure.

FIG. 8 is a perspective view depicting an upper receiver having a quickrelease ejection port dust cover, in accordance with an embodiment ofthe disclosure.

FIG. 9 is a perspective view depicting an ejection port dust cover, inaccordance with an embodiment of the disclosure.

FIG. 10A is a close-up, cross-sectional view depicting a portion of anejection port dust cover including a pin in a first, outwardly extendingposition, in accordance with an embodiment of the disclosure.

FIG. 10B is a close-up, cross-sectional view depicting the portion ofthe ejection port dust cover including the pin in a second, retractedposition, in accordance with an embodiment of the disclosure.

FIG. 11A is an exploded, perspective view depicting an indexing pin andindexing pin sheath of a barrel assembly, in accordance with anembodiment of the disclosure.

FIG. 11B is a perspective view depicting the assembled indexing pin andindexing pin sheath of the barrel assembly of FIG. 11A.

FIG. 12A is a perspective view depicting an indexing pin, in accordancewith a first embodiment of the disclosure.

FIG. 12B is a perspective view depicting the indexing pin of FIG. 12Apositioned on a barrel assembly, in accordance with an embodiment of thedisclosure.

FIG. 13A is a perspective view depicting an indexing pin, in accordancewith a second embodiment of the disclosure.

FIG. 13B is a perspective view depicting the indexing pin of FIG. 13Aincluded as part of a barrel assembly, in accordance with an embodimentof the disclosure.

FIG. 14A is a perspective view depicting an indexing pin, in accordancewith a third embodiment of the disclosure.

FIG. 14B is a perspective view depicting the indexing pin of FIG. 14Aincluded as part of a barrel assembly, in accordance with an embodimentof the disclosure.

FIG. 15A is a perspective view depicting an indexing pin, in accordancewith a fourth embodiment of the disclosure.

FIG. 15B is a perspective view depicting the indexing pin of FIG. 15Aincluded as part of a barrel assembly, in accordance with an embodimentof the disclosure.

While embodiments of the disclosure are amenable to variousmodifications and alternative forms, specifics thereof shown by way ofexample in the drawings will be described in detail. It should beunderstood, however, that the intention is not to limit the disclosureto the particular embodiments described. On the contrary, the intentionis to cover all modifications, equivalents, and alternatives fallingwithin the spirit and scope of the subject matter as defined by theclaims.

DETAILED DESCRIPTION

Referring to FIGS. 2A-H, a magnesium alloy upper receiver housing 150(hereinafter referred to as an “upper receiver” or “upper”), is depictedin accordance with an embodiment of the disclosure. It should beappreciated that the terms “AR-15,” “firearm,” “upper receiver” and“upper” are used for basic explanation and understanding of theoperation of the systems, methods and apparatuses of this disclosure.Therefore the terms “AR-15,” “firearm,” “upper receiver” and “upper” arenot to be construed as limiting the systems, methods, and apparatuses ofthis disclosure, and are to be understood broadly to include any firearmhaving a blowback operated system.

Generally, the upper receiver 150 can include a, right side wall 152,top wall 154, left side wall 156, and a bottom wall 158. In someembodiments, the right, top, left, and bottom walls 152, 154, 156, and158 can be included as sides in a general octagonal cross-sectionalconfiguration. Additionally, it should be appreciated that, depending onthe desired configuration of the upper receiver 150, the right side wall152 and the left side wall 156 can be alternated so that the left sidewall 156 becomes the right side wall 152, and the right side wall 152becomes the left side wall 156. The right, top, left and bottom walls152, 154, 156, and 158 can generally extend between a proximal end 160and a distal end 162. FIGS. 2B-G respectively depict the right side,top, left side, bottom, proximal end, and distal end views of the upperreceiver 150.

In one embodiment, the right, top, left and bottom walls 152, 154, 156,and 158 can define an upper receiver cavity 164. The cavity 164 cangenerally extend from a charging handle aperture 166 and bolt aperture168 (located in proximity to the proximal end 160) to a gas tubeaperture 170 and barrel aperture 172 (located in proximity to the distalend 162). The charging handle aperture 166 can generally be alignedalong a longitudinal axis of the upper receiver 150 with the gas tubeaperture 170. Likewise, the bolt aperture 168 can generally be alignedalong the longitudinal axis of the upper receiver 150 with the barrelaperture 172. In some embodiments, the upper receiver 150 can includebarrel nut threading 173 on the distal end 162 to enable coupling of theupper receiver 150 to a barrel. In some embodiments, the barrel nutthreading 173 can define an indexing notch 193 configured to receive acorresponding indexing pin of a barrel assembly, thereby inhibiting thebarrel assembly from rotating relative to the upper receiver housing 150when the upper receiver housing 150 and barrel assembly are operablycoupled to one another, for example via a barrel nut threaded on tobarrel nut threading 173.

An ejection port aperture 174 and a forward assist aperture 176(depicted in FIG. 2F) can be formed in the right side wall 152 of theupper receiver 150. In some embodiments, the right side wall 152 candefine a pair of ejection port dust cover retention slots 175A/B,configured to receive a dust cover (as described in further detailbelow). A forward assist cover 178 can extend outwardly from the rightside wall 152 to define the forward assist aperture 176. In oneembodiment, a forward assist fastener aperture 179 can be formed throughthe right side wall 152 and/or a portion of the forward assist cover178. In some embodiments, the right side wall 152 can further define abrass deflector channel 188, configured to receive a brass deflector (asdescribed in further detail below).

Depending upon the configuration, a carry handle (not depicted) orpicatinny rail portion 182 can be formed along the top wall 154 of theupper receiver 150. A pivot pin lug 184 and take down pin lug 186 canextend from the bottom wall 158 of the upper receiver 150, therebyenabling the upper receiver 150 to be operably coupled to a lowerreceiver.

With reference to FIG. 2H, the right, top, left, and bottom walls 152,154, 156, and 158 defining the upper receiver cavity 164, can furtherdefine a cutout 165 and ramp 167. During operation, the cutout 165 canbe configured to receive a portion of a bolt carrier group (specificallya cam pin head). The ramp 167, which can extend proximally from thecutout 165, can define a shallow angled slope (e.g., an angle of betweenabout 0.25° and about 10°) to provide a gradual transition between asurface 169 generally parallel to a longitudinal axis of the upperreceiver 150 and the cutout 165, thereby promoting smoother cycling ofthe bolt carrier group, and reducing frictional wear on interiorsurfaces of the upper receiver cavity 164.

It should be appreciated that a more detailed explanation of othercomponents of the upper receiver 150, instructions regarding how toattach and use the various components of the upper receiver 150, methodsfor installing related components of the upper receiver 150, and certainother items and/or techniques necessary for the implementation and/oroperation of various components of the AR-15 platform are not providedherein because such background information is known to one of ordinaryskill in the art. Therefore, it is believed that the level ofdescription provided herein is sufficient to enable one of ordinaryskill in the art to understand and practice the systems, methods and/orapparatuses as described herein.

In one embodiment, the upper receiver 150, including the right, top,left and bottom walls 152, 154, 156, and 158, can be constructed of ahigh-strength, lightweight metal alloy, such as magnesium; althoughother alloys, such as aluminum, titanium and steel can also be used. Forexample, in one embodiment, the upper receiver 150 can be machined froma high-strength, extruded stock of magnesium alloy having an extrudedcross-section shape near the net shape of the finished upper receiver150.

For example, in one embodiment, an extruded rail of magnesium alloy canhave an octagonally shaped cross-section generally defining the right,top, left and bottom walls 152, 154, 156, and 158 of the upper receiver150. Thereafter, the extruded rail can be machined to define the variousfeatures of the upper receiver 150, including, for example, the upperreceiver cavity 164, charging handle aperture 166, gas tube aperture170, ejection port aperture 174, forward assist aperture 176, picatinnyrail 182, pivot pin lug 184, take down pin lug 186, and/or otherfeatures and/or components. In one embodiment, approximately 70% of anexterior of the finished upper receiver 150 is machined, while theremaining approximate 30% of the exterior remains as in un-machinedstate, so as to have previously been defined by the extruded rail ofmagnesium alloy stock. In another embodiment, portions of the upperreceiver 150 can be forged.

Magnesium which is approximately 33% lighter than aluminum, 60% lighterthan titanium, and 75% lighter than steel has readily apparent weightadvantages over other materials in the construction of an upper receiver150, with similar strength characteristics to other constructionmaterials. However, magnesium alloys are considered less stable and moreprone to corrosion and/or electrolysis in comparison to other alloys,particularly in the presence of saltwater. Accordingly, despite thesignificant reduction in weight, if not properly cared for, componentsconstructed of magnesium alloys may have a shorter lifespan thancomponents constructed of more stable, corrosion and wear resistantmaterials.

A rapid breakdown of the upper receiver 150 constructed of a magnesiumalloy can be exacerbated by the heat and pressure experienced within theupper receiver cavity 164 during operation, as well as the highfrictional sliding force of the bolt carrier group each time the rifleis cycled, particularly as magnesium alloys are generally found to besofter than other metals, such as aluminum alloys. Accordingly,durability continues to be a major concern in the construction of anupper receiver 150 out of a magnesium alloy. In fact, conventionalwisdom suggests that it is not possible to construct an upper receiver150 out of a magnesium alloy with a usable lifetime or duration thatjustifies the expense of creating such an upper receiver 150.

Applicants of the present disclosure have discovered a solution to thisproblem through the application of a highly wear resistant, anodizedcoating to one or more surfaces of the magnesium alloy upper receiver150. Accordingly, upper receivers 150 of the present disclosure are ableto withstand the heat and pressure experienced within the upper receivercavity, as well as the high frictional sliding force of the bolt carriergroup during sustained operations, even when exposed to a variety ofharsh environmental conditions (e.g., exposure to saltwater).

In one embodiment, the anodized coating is applied to the upper receiver150 by generally immersing the machined upper receiver 150 in anelectrochemical bath containing a chemical slurry. The chemical slurrycan be formed of an aqueous electrolytic solution having a pH of atleast 12.5, and comprising between about 2 g/L and about 12 g/L of anaqueous soluble hydroxide, between about 2 g/L and about 15 g/L of afluoride containing composition selected from the group consisting offluorides and fluorosilicates, and between about 5 g/L and about 30 g/Lof silicate or between about 5 g/L and about 30 g/L of vanadate. In oneembodiment, one or more physical property modifying agents can be addedto the chemical slurry. The one or more physical property modifyingagents can be configured to improve surface hardness, increase surfacelubricity, modify the color, increase electrical conductivity, and thelike.

For example, in one embodiment, one or more surface hardening agents,such as zinc oxide (ZnO), micro-sized industrial diamond particles(e.g., particles of C having a size of between about 0.1 and about 100μm), nano-sized industrial garnet particles (e.g., particles ofA₃B₂Si₃O₁₂ having a size of between about 1 nm and about 100 nm),silicon carbide (SiC), and/or aluminum oxide (Al₂O₃), can be added tothe chemical slurry to increase the surface hardness and improveabrasion resistance of the upper receiver 150. In one embodiment, one ormore surface lubricity agents, such as micro-sized Teflon™ spheres((C₂F₄)_(n)) and/or a solid lubricant, such as molybdenum disulfide(MoS₂), can be added to the chemical slurry to increase the surfacelubricity of the upper receiver 150. In one embodiment, agentsconfigured to modify the color of the anodized coating, agents toimprove the electrical conductivity of the anodized coating, as well asother agents to modify or improve the physical properties of theanodized coating can be added to the chemical slurry. In one embodiment,the one or more physical property modifying agents or combinationsthereof can be added to the chemical slurry in the amount of betweenabout 1 g/L and about 150 g/L.

Referring to FIG. 3, a schematic diagram depicting a system 200 forapplying an anodized coating to an upper receiver 150 is depicted inaccordance with an embodiment of the disclosure. Prior to applying theanodized coating, the upper receiver 150 can optionally be pretreated todegrease or cleanse the surface of the upper receiver 150 and/or tocreate a desirable base over at least a portion of the surface of theupper receiver 150. In other embodiments, the upper receiver 150 can beimmersed in the chemical slurry 202 without preconditioning.

While immersed in the slurry 202, an electrical potential and/or currentcan be applied to the upper receiver 150 via a rectifier 204. In oneembodiment, the rectifier 204, which can be in electrical communicationwith a voltage source 206, can be configured to produce a wave signalconfigured to drive the anodized coating process. In one embodiment, therectifier 204 can have an output voltage potential of between about 150volts and about 360 volts; although other output voltages of therectifier 204 are also contemplated.

To apply the electrical potential and/or current across the upperreceiver 150, an anode 208 in electrical communication with therectifier 204 can be placed in electrical communication with the upperreceiver 150 (such that the upper receiver 150 effectively becomes theanode 208). A cathode 210, also in electrical communication with therectifier 204 can be placed elsewhere within the chemical slurry 202, soas to create an electrical potential between the cathode 210 and theupper receiver 150 through at least a portion of the slurry 202, suchthat the upper receiver 150 generally has a positive charge. In anotherconfiguration, the position of the anode 208 and the cathode 210 can bereversed, such that the upper receiver 150 generally has a negativecharge.

During the anodized coating process, the slurry 202 can be agitated orcirculated within the electrochemical bath 212, such that the slurry 202(which can be a heterogeneous mixture) remains in suspension. In oneembodiment, a magnetic stir plate can be utilized to agitate the slurry202 within the electrochemical bath 212. In other embodiments, theslurry 202 can be circulated via a pump 214. Such a configuration can beparticularly useful where certain components of the slurry 202 have atendency to settle at the bottom of the electrochemical bath 212 duringthe anodized coating process. Accordingly, the pump 214 can continuouslypull a quantity of slurry 202 through one or more outlets or drains 216,and reintroduce the quantity of slurry 202 into the electrochemical bath212 through one or more inlets or jets 218, thereby inhibitingseparation of the slurry 202. In one embodiment, the pump 214 can serveto pressurize the slurry 202, such that reintroduction of the slurry 202into the electrochemical bath 212 occurs under force. In one embodiment,the one or more inlets 218 can be formed as nozzles configured toimprove agitation and overall mixing of the slurry 202.

In one embodiment, the pump 214 can further be configured to route aquantity of slurry 202 through a heat exchanger 220, which can be incommunication with a heat sump 222. The heat exchanger 220 and heat sump222 can be configured to maintain the slurry at a desired temperature,or at least partially control or slow a natural increase in the slurry202 temperature during the anodized coating process. For example, in oneembodiment, the slurry 202 can be maintained at a temperature of betweenabout 2° C. and about 20° C. over the course of the anodized coatingprocess; although other temperatures of the slurry 202 are alsocontemplated. In an alternative embodiment, a heat exchanger or chiller(for example in the form of a coil) can be positioned directly withinthe electrochemical bath 212; particularly where a magnetic stir plateis utilized to agitate the slurry 202.

Accordingly, the above described anodized coating results in the growthof an oxide layer over the surface of the upper receiver 150. The growthresults in an irregular porous ceramic-like magnesium-oxide layer fromthe magnesium with the effect of improving or altering hardness,abrasion resistance, surface lubricity, color and/or electricalconductivity of the upper receiver 150. In some embodiments, the entireupper receiver 150 can be submerged in the chemical slurry 202. In otherembodiments, anodized coating of the upper receiver 150 can be limitedto specific surfaces, such as the upper receiver cavity 164 or otherareas subject to repetitive wear, heat, pressure and/or abrasion.

In addition to providing superior hardness, abrasion resistance andsurface lubricity to the upper receiver, thereby enabling an extendedproduct life, the porous nature of the anodized coating can additionallyserve as a base, offering excellent adhesion for an optional surfacetreatment. Accordingly, in some embodiments, the upper receiver 150 canbe coated with a topcoat surface treatment, such as paint and/or alubricity enhancing sealant or agent. For example, in one embodiment,the upper receiver 150 can be sealed via an electrophoretic paintingprocess (E-Coat), and/or one or more layers of an applied solid filmlubricant, Teflon®, and/or Cerakote® ceramic coating. Other surfacecoating treatments are also contemplated.

Referring to FIG. 4, a method 300 of making an upper receiver 150 isdepicted in accordance with an embodiment of the disclosure. At 302, asection of magnesium alloy extrusion stock can be machined to define thevarious features of the upper receiver 150. For example, in oneembodiment, the magnesium alloy extrusion stock can be machined todefine an upper receiver cavity 164, charging handle aperture 166, gastube aperture 170, ejection port aperture 174, forward assist aperture176, picatinny rail 182, pivot pin lug 184, take down pin lug 186,and/or other features and/or components of the upper receiver 150. Inone embodiment, approximately 70% of the surface of the magnesium alloystock can be machined to define the various features of the upperreceiver 150. In another embodiment, portions of the upper receiver 150can be forged.

At 304, an anodized coating can be applied to one or more surfaces ofthe machined upper receiver 150. For example, in one embodiment, themachined upper receiver 150 can be immersed in a chemical slurry 202while an electrical potential is applied to the upper receiver 150 todrive the anodized coating process. In some embodiments, the anodizedcoating can include one or more surface hardening agents, one or moresurface lubricity agents, and/or one or more physical property modifyingagents. In some embodiments, the upper receiver 150 can optionally bepretreated to degrease or cleanse the surface of the upper receiver 150prior to immersing the upper receiver 150 in the chemical slurry 202.

At 306, the upper receiver 150 can optionally be coated with a topcoatsurface treatment, such as a paint and/or lubricity enhancing agent.Accordingly, embodiments of the present disclosure provide a method ofconstructing a lightweight upper receiver 150 out of a magnesium alloyhaving a hardened surface that enables the upper receiver 150 towithstand the high temperatures, pressures, and frictional slidingforces present within the upper receiver group of a semi-automaticfirearm, particularly those present within the upper receiver cavity164.

It should be understood that the individual steps used in the methods ofthe present teachings may be performed in any order and/orsimultaneously, as long as the teaching remains operable. Furthermore,it should be understood that the apparatus and methods of the presentteachings can include any number, or all, of the described embodiments,as long as the teaching remains operable.

In addition to the upper receiver cavity 164, another area of the upperreceiver 150 particularly prone to wear is the brass deflector 180. Withreference to FIG. 5, during operation of the rifle 100, spent shellcasings 126 (frequently referred to as “brass”) ejected from the upperreceiver cavity 164 impact the brass deflector 180, which serves togenerally direct the ejected brass 126 along an ejection trajectory 128.In some embodiments, to inhibit wear from repeated impact with ejectedbrass 126, the brass deflector 180 can be constructed of a materialother than a magnesium alloy, such as steel, aluminum, plastic, and/orresin; although construction of a brass deflector 180 out of a magnesiumalloy having a hardened anodized coating is also contemplated.

With reference to FIG. 6A, in some embodiments, the upper receiver 150can be machined to include a brass deflector channel 188, into which thebrass deflector 180 can be slidably positioned. For example, in oneembodiment, the brass deflector channel 188 can be configured as adovetail groove extending proximally from the ejection port aperture174. Accordingly, the brass deflector 180, having a brass deflectingsurface 190, can be slidably positioned within the brass deflectorchannel 188. In one embodiment, the brass deflector 180 can be fixed inposition relative to the upper receiver 150 via a set screw 192.Accordingly, the deflecting surface 190 can be configured to generallydirect the ejected brass 126 along the ejection trajectory 128.

In some embodiments, it may be desirable to tailor or modify thetrajectory 128 of the ejected brass 126; particularly, when it isdesirable to restrict ejection of the brass 126 to a direction or area,for example when firing in close proximity to other individuals or tightquarters. Accordingly, as depicted in FIG. 6B, in one embodiment, anangle □ (e.g., between about 20° and about 90°) of the deflectionsurface 190A of the brass deflector 180 can be increased or decreased asdesired to modify the trajectory 128 of the ejected brass 126. Asdepicted in FIG. 6C, in yet another embodiment, the deflection surface190B can include an arc or curve, as desired to modify the trajectory128 of the ejected brass 126. Other angles and contours of deflectionsurface 190 to modify the trajectory 128 of the ejected brass 126 arealso contemplated.

In some embodiments, the upper receiver 150 can be sold as a kitincluding several brass deflectors 180, each having a deflection surface190 specifically tailored to direct the ejected brass 126 along adesirable trajectory 128. For example, in one embodiment, a first brassdeflector 180 can be configured to direct the brass 126 along atraditional ejection trajectory 128, a second brass deflector 180 can beconfigured to direct the ejected brass 126 towards the ground and/orfeet of the user in a rapid manner, and a third brass deflector 180 canbe configured to direct ejected brass 126 over a shoulder of the user.Other desirable ejection trajectories are also contemplated.

With reference to FIG. 7, in yet another embodiment, the brass deflector180 can be configured to be adjusted by the user to modify thetrajectory 128 of the ejected brass 126. For example, in one embodiment,brass deflector 180 can include a base 194 an adjustable member 196including a deflecting surface 190, and a fastener 198. In operation,the base 194 can be operably coupled to the upper receiver 150, forexample, slidably received within the deflector channel 188. Theadjustable member 196 can be rotated as desired to achieve the desiredejection trajectory 128, and secured in a fixed position relative to thebase 194 via fastener 198. Thereafter, adjustments to the ejectiontrajectory 128 can be accomplished via loosening the fastener 198 andmoving the base 194 forward or aft within the deflector channel 188and/or rotating the adjustable member 196 relative to the base 194.

With reference to FIG. 8, a further improvement to the upper receiver150 can include a quick release ejection port dust cover 177, configuredto selectively pivot between a first position, in which the ejectionport aperture 174 is covered (as depicted in FIG. 8) to inhibit dust anddebris from entering the ejection port aperture 174, and a secondposition, in which the ejection port aperture 174 is uncovered therebyenabling the ejection of brass therefrom.

Upper receivers of AR-15 type firearms typically include an ejectionport dust cover. Such dust covers often break or have some other type ofmalfunction, requiring removal and replacement. However, removal andreplacement of a conventional dust cover is generally considered to be adifficult process, often requiring the removal of the barrel from theupper receiver in order to remove a pivot pin running the length of thedust cover, which serves to pivotably retain the dust cover with respectto the upper receiver.

The quick release ejection port dust cover 177 of the present disclosureaddresses this problem through replacement of the single, long pivot pinwith a pair of opposed, outwardly biased pins 179A/B configured toextend at least partially into the ejection port dust cover retentionslots 175A/B defined by the upper receiver 150, thereby promoting theease in removal of the ejection port cover 177 from the upper receiver150, and without the need to remove the barrel or other components fromthe upper receiver 150. An additional advantage of this feature is thatthe ejection port dust cover retention slots 175A/B are more easilymachined than the aperture required for a pivot pin running the lengthof the dust cover with conventional dust covers, thereby presenting atime and cost savings in the manufacture of the upper receiver 150. Forexample, in some embodiments, the dust cover retention slots 175A/B canbe machined with a “lollipop” bit, as opposed to the drilling of a 3inch long, ⅛ inch diameter aperture, as is required to accommodate thelonger pivot pins of conventional dust covers.

With reference to FIG. 9, in one embodiment, the dust cover 177 caninclude a panel 181 configured to selectively cover the ejection portaperture 174. The panel 181 can be constructed of any suitable rigidmaterial, such as metal, polymer, or composite. In one embodiment, thepanel 181 can define one or more channel 183 running lengthwise alongone edge of the panel 181 and configured to receive the pins 179A/B anda spring retention rod 185. The spring retention rod 185 can beconfigured to retain a biasing member 187 in position relative to thepanel 181, the biasing member 187 configured to bias the dust cover 177to the second, open position when operably coupled to the upper receiver150. In some embodiments, the panel 181 can further include a latch 189configured to selectively retain the dust cover 177 in the first, closedposition relative to the upper receiver 150.

FIG. 10A depicts a close-up, cross-sectional view of one of the pins179A in a first, outwardly extending position, while FIG. 10B depictsthe pin 179A in a second, retracted position. As depicted, a biasingmember 191 can be positioned between a portion of the pin 179A and thepanel 181, thereby naturally biasing the pin 179A to the first,outwardly extending position, and in a manner which naturally retains apivotable connection between the dust cover 177 and the upper receiver150 (as depicted by FIG. 8). When removal of the dust cover 177 isdesired, a user can insert a small rigid object (e.g., the tip of thescrewdriver, pen, or toothpick) into either of the retention slots175A/B to force the pin 179A/B to the second, retracted position,thereby enabling removal of the dust cover 177 from the upper receiver150.

As previously described, in some embodiments, the barrel nut threading173 can define an indexing notch 193 (as depicted in FIG. 2A) configuredto receive a corresponding indexing pin of a barrel assembly. Referringto FIG. 11A, an indexing pin 195 of a barrel assembly 201 is depicted inaccordance with an embodiment of the disclosure. Capture of the indexingpin 195 of the barrel assembly 201 within the indexing notch 193 of theupper receiver 150 can serve to inhibit the barrel assembly 201 fromrotating relative to the upper receiver 150 during assembly.Misalignment of the barrel assembly 201 and upper receiver 150 canresult in impingement of actuatable firing components which partiallyextend into the barrel assembly (e.g., an extractor) during operation ofthe firearm. In some circumstances, the impingement can result in thefirearm “jamming” or failing to cycle properly. Misalignment may also(either directly or indirectly) interfere with accuracy, as the gunsights may not be properly oriented with respected to the intendedtrajectory of the bullet.

In some cases, when a torque is applied to the barrel assembly 201(e.g., during assembly or attachment of threaded connections to themuzzle), the sole element inhibiting the barrel assembly 201 fromrotating relative to the upper receiver 150 is the indexing pin 195.Where the force and/or pressure between the indexing pin 195 and thenotch 193 exceed the material properties of the upper receiver 150and/or barrel assembly 201, permanent deformation to the components canoccur. The use of softer materials (e.g., fabrication of the upperreceiver 150 out of a magnesium alloy) can exacerbate this problem.

Applicants of the present disclosure have addressed this problem bydeveloping an indexing pin 195 and/or indexing pin sheath 203 configuredto disburse the force over a larger surface area (thereby reducing thepressure experienced between the notch 193 and indexing pin 195). Forexample, with reference to FIGS. 11A-B, in one embodiment an indexingpin sheath 203 can be applied to an existing (standard sized) indexingpin 195. In embodiments, the indexing pin sheath 203 can include aplanar surface 205 configured to increase the surface area contact withthe indexing notch 193, thereby disbursing the force experienced as aresult of torque applied to the barrel assembly 201 over a larger areaof the notch 193.

In other embodiments, the indexing pin 195 and sheath 203 can beconfigured as a single, unitary component intended to replace anexisting indexing pin 195. For example with reference to FIGS. 12A-B, areplacement indexing pin 207 is depicted in accordance with anembodiment of the disclosure. In such an embodiment, the replacementindexing pin 207 can include a substantially round post portion 209configured to fit within a predefined aperture within the barrelassembly 201 (e.g., the aperture from which the indexing pin 195 isremoved), and a polygonal upper portion 211 having a planar surface 205configured to increase the surface area contact with the indexing notch193. In some embodiments, the polygonal upper portion 211 can generallyassume the shape of a square, rectangle, or other polygon. In otherembodiments, the upper portion 211 can have an elliptical, irregular orother than polygonal shape, which in some embodiments can be keyed tothe notch 193 of the upper receiver 150 to inadvertent inhibit rotation.In some embodiments, the corners of the upper portion 211 can befilleted which can contribute to ease in insertion of the indexing pin207 into the notch 193 during assembly of the barrel assembly 201 to theupper receiver 150.

As depicted in FIGS. 13A-14B, in other embodiments, the replacementindexing pin 207′ and 207″ can be a polygonal or elliptical plugconfigured to be received within a correspondingly shaped aperture 213defined in the barrel assembly 201. As depicted in FIGS. 15A-B, in yetother embodiments, the barrel assembly 201 can define a notch 215 intowhich the replacement indexing pin or key 207′″ can be received. In someembodiments, the indexing pin 207 (or sheath 203) can be constructed ofa suitable, compatible material such as a steel, aluminum or magnesiumalloy. In some embodiments, the indexing pin 207 (or sheath 203) can beconstructed of a material configured to absorb stress or shock tofurther inhibit permanent damage or deformation to the upper receiver150 when a torque is applied to the barrel assembly 201.

Various embodiments of systems, devices, and methods have been describedherein. These embodiments are given only by way of example and are notintended to limit the scope of the claimed inventions. It should beappreciated, moreover, that the various features of the embodiments thathave been described may be combined in various ways to produce numerousadditional embodiments. Moreover, while various materials, dimensions,shapes, configurations and locations, etc. have been described for usewith disclosed embodiments, others besides those disclosed may beutilized without exceeding the scope of the claimed inventions.

Persons of ordinary skill in the relevant arts will recognize that thesubject matter hereof may comprise fewer features than illustrated inany individual embodiment described above. The embodiments describedherein are not meant to be an exhaustive presentation of the ways inwhich the various features of the subject matter hereof may be combined.Accordingly, the embodiments are not mutually exclusive combinations offeatures; rather, the various embodiments can comprise a combination ofdifferent individual features selected from different individualembodiments, as understood by persons of ordinary skill in the art.Moreover, elements described with respect to one embodiment can beimplemented in other embodiments even when not described in suchembodiments unless otherwise noted.

Although a dependent claim may refer in the claims to a specificcombination with one or more other claims, other embodiments can alsoinclude a combination of the dependent claim with the subject matter ofeach other dependent claim or a combination of one or more features withother dependent or independent claims. Such combinations are proposedherein unless it is stated that a specific combination is not intended.

Any incorporation by reference of documents above is limited such thatno subject matter is incorporated that is contrary to the explicitdisclosure herein. Any incorporation by reference of documents above isfurther limited such that no claims included in the documents areincorporated by reference herein. Any incorporation by reference ofdocuments above is yet further limited such that any definitionsprovided in the documents are not incorporated by reference hereinunless expressly included herein.

For purposes of interpreting the claims, it is expressly intended thatthe provisions of 35 U.S.C. § 112(f) are not to be invoked unless thespecific terms “means for” or “step for” are recited in a claim.

What is claimed is:
 1. A firearm upper receiver, comprising: a magnesiumalloy housing defining an upper receiver cavity having an interiorsurface shaped and sized to enable actuation of a bolt carrier grouptherein during a firearm actuation cycle, at least a portion of theinterior surface coated with a hardened anodized coating configured toslow operational wear of the interior surface generated by heat,pressure and frictional forces during a firearm actuation cycle toensure a functional life of the magnesium alloy housing of at least 500firearm actuation cycles.
 2. The firearm upper receiver of claim 1,wherein the hardened anodized coating includes a magnesium-oxide layer.3. The firearm upper receiver of claim 2, wherein the magnesium-oxidelayer includes one or more hardening agents embedded therein.
 4. Thefirearm upper receiver of claim 1, wherein the hardened anodized coatingis treated with a topcoat surface treatment.
 5. The firearm upperreceiver of claim 4, wherein the topcoat surface treatment is at leastone of an electrophoretic paint and/or lubricity enhancing agent.
 6. Thefirearm upper receiver of claim 1, further comprising a brass deflector.7. The firearm upper receiver of claim 6, wherein the brass deflector ispositionable relative to the magnesium alloy within a deflector channeldefined by the magnesium alloy housing.
 8. The firearm upper receiver ofclaim 6, wherein the brass deflector includes a deflecting surfaceconfigured to impart directional control on brass ejected from themagnesium alloy housing during firearm actuation.
 9. The firearm upperreceiver of claim 1, further comprising a quick release ejection portdust cover.
 10. A method of making a firearm upper receiver, comprising:machining a housing including an upper receiver cavity out of a stock ofextruded magnesium alloy; and applying a hardened anodized coating to atleast a portion of an interior surface of the upper receiver cavity toslow operational wear of the interior surface generated by heat,pressure and frictional forces during a firearm actuation cycle toensure a functional life of the housing of at least 500 firearmactuation cycles.
 11. The method of claim 10, wherein the hardenedanodized coating includes a magnesium-oxide layer.
 12. The method ofclaim 11, wherein the magnesium-oxide layer includes one or morehardening agents embedded therein.
 13. The method of claim 10, furthercomprising applying a topcoat surface treatment to the hardened anodizedcoating.
 14. The method of claim 13, wherein the topcoat surfacetreatment is at least one of an electrophoretic paint and/or lubricityenhancing agent.
 15. The method of claim 10, further comprising a brassdeflector.
 16. The method of claim 15, wherein the brass deflector ispositionable relative to the magnesium alloy within a deflector channeldefined by the magnesium alloy housing.
 17. The firearm upper receiverof claim 10, further comprising a quick release ejection port dustcover.
 18. A firearm upper receiver kit, comprising: a magnesium alloyhousing defining an upper receiver cavity having an interior surface, atleast a portion of the interior surface coated with a hardened anodizedcoating configured to slow operational wear of the interior surfacegenerated by heat, pressure and frictional forces during a firearmactuation cycle to ensure a functional life of the magnesium alloyhousing of at least 500 firearm actuation cycles; and one or more brassdeflector including a deflecting surface configured to impartdirectional control on brass ejected from the magnesium alloy housingduring firearm actuation.
 19. The firearm upper receiver kit of claim18, wherein the brass deflector is constructed of a material other thana magnesium alloy.
 20. The firearm upper receiver kit of claim 18,wherein the brass deflector is positionable relative to the magnesiumalloy within a deflector channel defined by the magnesium alloy housing.